Purpose<i>PIK3CA</i>, encoding for subunit p110a of phosphatidylinositol 3 kinase, is frequently mutated in breast cancer. <i>PIK3CA</i>mutation was predictive for pathological complete response (pCR) in human epidermal growth factor 2 positive breast cancer. This study explores the association of <i>PIK3CA</i> mutation and pCR in triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy.Materials and MethodsA total of 92 patients with TNBC derived from a prospectively randomized phase II trial GeparSixto study (NCT01426880). Exon 9 and exon 20 of <i>PIK3CA</i> mutations were evaluated by using classical Sanger method with formalin-fixed paraffin-embedded tumor tissues.ResultsSeven of 90 tumors (7.8%) were detectable with a <i>PIK3CA</i> H1047R mutation. Overall, <i>PIK3CA</i> H1047R mutation was significantly associated with a lower pCR rate (14.3% vs. 56.6%; odds ratio, 0.128; 95% confidence interval [CI], 0.015 to 1.108; p=0.047). In carboplatin- containing treatment patients, H1047R mutation trended to predict a lower pCR rate (20% vs. 62.5%; p=0.146). In a multivariable analysis, H1047R mutation trended to predict a lower pCR rate (hazard ratio, 0.1; 95% CI, 0.01 to 1; p=0.056).ConclusionTNBC with a <i>PIK3CA</i> H1047R mutation was less likely to achieve pCR after anthracyclinebased neoadjuvant chemotherapy. Development of H1047R mutant selective inhibitors might be helpful to conquer this subtype of breast cancer.
Pathological complete response to neoadjuvant chemotherapy, but not the addition of carboplatin, is associated with improved survival in Chilean triple negative breast cancer patients: a report of real world data
